1. Field of the Invention
The invention relates to a clamp structure, and more particularly, to a clamp structure of an external electrode lamp.
2. Description of the Prior Art
Most lamps used in TFT-LCD backlight modules today are cold cathode fluorescent lamps (CCFL) and the electrodes of these lamps are essentially sealed inside the lamp. The electrode however, also contains a conducting end that extends from the internal electrode to an external conducting wire, and eventually connects to a power supply to light the lamp.
The conducting end of the CCFL essentially needs to be connected via welding or a copper belt to the conducting wire. Nevertheless, welding or copper belting are both complicated processes that also bear high failure rates. For example, poor soldering often causes a so-called fake welding effect, in which the heat generated during lighting will produce temperature high enough to melt the solder of the section where the conducting end is connected to the conducting wire and eventually results in a broken circuit. If the excess solder of the section between the conducting end and the conducting wire is poor, an electric discharge often results and causes serious scorch or electric leakage. On the other hand, if copper belting is used, electric discharge at the four corners of the copper belt has to be considered carefully, and in general, an additional insulated heat-shrink tube is added to cover the external area of the copper belt which unavoidably results in extra cost.
Taiwan Patent No. 00540745 provides a backlight device that includes a set of lamps located inside a main structure in which each of the lamps contains a conducting end that extends from the internal lamp. The main structure includes a plurality of supporting devices in which each of the devices contains a hole that is capable of holding a lamp and one conducting part that connects mechanically as well as electrically to the conducting end of the lamp. Despite the fact that this patent design could essentially solve the problems discussed previously, the luminosity and life expectancy of the lamp have been strongly challenged as the development of backlight lamp advances and as the size of LCD panel increases. In order to cope with these challenges, the external electrode fluorescent lamp (EEFL) has been introduced to the market.
The EEFL is a type of illuminating device for transforming electrical energy released via high frequencies into light energy. In contrast to other fluorescent lamp that uses the electrode to transform external electrical energy to the energy needed by the lamp, the EEFL utilizes the principle of electromagnetic induction and a pair of metal electrodes covering the lamp to generate an induced current internally. The pair of metal electrodes covering the lamp is essentially being used as a primary coil of an adapter whereas the lamp is being used as a secondary coil of an adapter.
Under the same electrical current, the luminosity of the light produced by the external electrode lamp is essentially higher than that produced by the cold cathode fluorescent lamp. As a result of rapid advancement in the EEFL and its inverter manufacture technology, the external electrode lamps have been gradually adopted into the TFT-LCD backlight modules. Moreover, the life expectancy of external electrode lamps is also significantly longer than cold cathode fluorescent lamps in that CCFL generally lasts 60,000 hours whereas the EEFL is able to last 80,000 to 100,000 hours.
Despite the fact that the EEFL in general exhibits greater efficiency over CCFL, it still has some disadvantages. During regular testing, as the electrode of the EEFL is constantly driven by high voltages and exposed to the outside environment, numerous electric shocks would frequently take place. In addition, the layout of the electrode power supply resulting from stabilizing the external electrode lamp in position also places various limitations on the shock resistance design. Consequently, many of the EEFL products sold in the market today still suffer from problems such as poor electrode cladding or poor shock resistance.